There is a very good reason to get a high potential player through his ELC as early as possible. Let's say we burn a year of his deal this year, he comes into the league next year, scores 30-ish... then the year after he scores 40-ish. Then he's an RFA and we sign him to 2nd contract in line with what he produced in his first two years. Then in his first year of his 2nd deal, he breaks out to a 60-70 point player (or better). That kind of progression isn't uncommon and, this way, you've already got him under contract for very cheap relative to his production.
Now let's look at the other scenario, where he doesn't burn a year, but follows the same progression. How much more expensive will his contract be after putting up 60-70 points? It won't be nearly the bargain.